In a conventional 3rd-Generation Partnership Project (3GPP) system, a Radio Network Controller (RNC)/Base Station Controller (BSC) may perform Radio Resource Management (RRM) by analyzing a stored International Mobile Subscriber Identity (IMSI) of User Equipment (UE) to determine which frequency layer is preferentially used for the UE, so as to implement a radio access procedure. For example, in an IMSI Based Handover, the RNC/BSC may obtain subscription information of the UE by analyzing the IMSI of the UE, and allocate resources or parameters used for radio access to the UE according to the subscription information of the UE, so as to implement the radio access procedure.
A conventional System Architecture Evolution (SAE) system or Long Term Evolution (LTE) system also support an RRM strategy based on the subscription information of the UE. For example, in an Evolution-Universal Mobile Telecommunication System Terrestrial Access Network (E-UTRNA), an evolved base station (eNodeB) may determine the priority of cell reselection of the UE according to Radio Access Technology (RAT)/Frequency Selection Priority (RFSP) information contained in the subscription information of UE, and determine different frequency stratums or different RATs used for the UE in a re-direction connection mode.
However, for security, the eNodeB does not store the IMSI of the UE, and thus is unable to obtain the RAT/Frequency Selection Priority information of the UE by analyzing the IMSI of the UE. Hence, the eNodeB can not obtain the RAT/Frequency Selection Priority information of the UE unless another entity, e.g. a Mobile Management Entity (MME), notifies the eNodeB.
In the prior art, in an initial attach procedure, a Home Subscriber Server (HSS) provides the RAT/Frequency Selection Priority information of the UE to the MME; after receiving the information, if it is determined that the UE is in a non-roaming state, the MME directly stores the information; if it is determined that the UE is in a roaming state, the MME firstly modifies the information according to a strategy of a visit network in which the UE is located currently, and then stores the information. FIG. 1 is a schematic diagram illustrating a conventional initial attach procedure. As shown in FIG. 1, in Step 10, the HSS sends the MME an Insert Subscriber Data message containing the RAT/Frequency Selection Priority information of the UE.
According to the mode shown in FIG. 1, the MME is able to obtain the RAT/Frequency Selection Priority information of the UE. But it is can be seen according to the above description, it is the eNodeB that really needs the information. However, it is not described in the prior art how the MME notifies the eNodeB of the obtained RAT/Frequency Selection Priority information of the UE.
Meanwhile, after an operator modifies the subscription information of UE stored in the HSS, the HSS also sends the MME the Insert Subscriber Data message to notify the MME that the RAT/Frequency Selection Priority information of the UE has been modified, but the MME also merely stores the information, rather than triggers other procedures. That is to say, it is also not described in the prior art how the MME notifies the eNodeB of the modified RAT/Frequency Selection Priority information of the UE.
It is can be seen that, in the prior art, the eNodeB can not obtain the needed RAT/Frequency Selection Priority information of the UE because it can not receive the notification from the MME, and thus can not perform Radio Resource Management (RRM) according to the information, thereby influencing system performance.